U.S. Pat. No. 4,987,792 discloses a shift device for an automatic transmission operable in a manual ratio change mode. The shift device has a select lever, which may be manipulated for manually controlling a shift after conditioning the automatic transmission for operation in manual ratio change mode. An operator manipulates the select lever to indicate an operator up or downshift demand. The operator shift demand is applied to a transmission control unit. In response to the operator shift demand, the transmission control unit generates a shift demand. This shift demand is applied to a ratio control actuator. The ratio control actuator is activated in response to the shift demand and makes a ratio change.
U.S. Pat. No. 5,520,066 discloses a shift device in the form of a manually operable up-down select switch mounted to a steering wheel. An operator manipulates the up-down select switch to indicate an operator shift demand. The operator shift demand is applied to a transmission control unit. In response to the operator shift demand, the transmission control unit generates a shift demand. The shift demand is applied to a ratio control actuator. The ratio control actuator is activated in response to the shift demand and makes a ratio change.
The prior art devices are fairly well developed. However, a need remains for further development of such devices in light of current movement to a shift device that increases user satisfaction.